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IC447


PatrickGilliland
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I don't think this is a big deal at all but I was suddenly worried that the TEC optics might be inventing blue stars, or at least leading me to exaggerate the blue in some cases. Here is a sample of blue stars checked against the B-V colour index provided in SkyMap Pro 11. Scroll down to the second chart on this page for a chart. http://zebu.uoregon.edu/disted/ph122/dlec13.html

IC 447 Blue Star colour index.jpg

They look OK to me. My method, as usual, was to shoot equal colour and then run DBE, after which I use Noel's Increase Star Colour to pull colour from the edges into the cores. I haven't 'led' the colour at all.

Olly

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45 minutes ago, ollypenrice said:

I don't think this is a big deal at all but I was suddenly worried that the TEC optics might be inventing blue stars, or at least leading me to exaggerate the blue in some cases. Here is a sample of blue stars checked against the B-V colour index provided in SkyMap Pro 11. Scroll down to the second chart on this page for a chart. http://zebu.uoregon.edu/disted/ph122/dlec13.html

 

They look OK to me. My method, as usual, was to shoot equal colour and then run DBE, after which I use Noel's Increase Star Colour to pull colour from the edges into the cores. I haven't 'led' the colour at all.

Olly

4

Looks good to me!  If you look carefully just a difference in processing styles here I suspect.  Your stars are probably the same colour as mine.  You halo is more blue.  I just try to not let the halo's on my version be too different from the central star.  Just me personal preference when processing.  Maybe I should look at making more blue then bleeding in the colour to the start which i prefer.

Paddy

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2 hours ago, PatrickGilliland said:

Looks good to me!  If you look carefully just a difference in processing styles here I suspect.  Your stars are probably the same colour as mine.  You halo is more blue.  I just try to not let the halo's on my version be too different from the central star.  Just me personal preference when processing.  Maybe I should look at making more blue then bleeding in the colour to the start which i prefer.

Paddy

Paddy & Olly

this is getting interesting. Since I started in AP I wondered about if there were any true colours in what we are doing or if it was becoming rather arbitrary after a few rounds of processing (at least I got the feeling that my results were drifting towards the arbitrary). So, what about the yellow and red stars? Here (lower left corner) I marked some stars that are clearly white in the crop of Paddy's image and red in Olly's.

 

 

Edited by gorann
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Well, those are small stars which are going to be hard to identify and hard to find in the professional databases. Feel free to try! I was shooting with larger aperture which might account for the difference. Tom has this data from the same scope as Paddy. Maybe he can see what he caught. I'm not goiing to get over excited about this though! Maybe a new thread to avoid hijacking Paddy's.

Olly

 

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3 minutes ago, ollypenrice said:

Well, those are small stars which are going to be hard to identify and hard to find in the professional databases. Feel free to try! I was shooting with larger aperture which might account for the difference. Tom has this data from the same scope as Paddy. Maybe he can see what he caught. I'm not goiing to get over excited about this though! Maybe a new thread to avoid hijacking Paddy's.

Olly

 

 

 

15 minutes ago, gorann said:

 

 

My view is if you push the star colour more you will get the halo area with colour, you can then 'find' star colour if you want that way.  I can make my stars look like that but simply chose not to.   We are trying to make pleasing images and the variances between processing styles are good to see.  If we want to worry about being 100% technically correct all the time there is a lot more to consider than just this limited thread.  Work with the data you have.  If it looks nice all is well :)   It's an interesting point on accuracy but think we have to accept sometimes aesthetic appearance is part of what we do, and we all have our own take on that. 

It links back to Sara point on being accurate and our responsibility. Push too hard and it's false, don't push enough and same is true.  I just try to let the data do the work and accept it (for now) but seed planted and may review again in the future.

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Interestingly, looking at your two images, it appears that only the small red/yelloe stars differ in colour. Nice to hear that you both feel relaxed about it, then I am relaxed too!

Good night since the sky is cloudy over here...

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Sorry for hijacking the thread, but I have a thought here. Hmm, so Ollys blue stars contain more blue? If we disregard scope types and Noels actions and think about this in a scientific way instead, there might be other reasons to star colour differences. Atmosphere eats up the blue light and a higher elevation of the object photographed increases its relative colour intensity. Did you compare your altitude above mean sea level and the elevation of the object when photographed? I might be very wrong here, but I suppose Olly is situated quite a bit higher up than most of us, and thus get a little star colour bonus. In reality, this might be so small that its unnoticeable, but at least its an interesting thought! 

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7 hours ago, Mr Bergman said:

Sorry for hijacking the thread, but I have a thought here. Hmm, so Ollys blue stars contain more blue? If we disregard scope types and Noels actions and think about this in a scientific way instead, there might be other reasons to star colour differences. Atmosphere eats up the blue light and a higher elevation of the object photographed increases its relative colour intensity. Did you compare your altitude above mean sea level and the elevation of the object when photographed? I might be very wrong here, but I suppose Olly is situated quite a bit higher up than most of us, and thus get a little star colour bonus. In reality, this might be so small that its unnoticeable, but at least its an interesting thought! 

It cannot be explained by elevation since Paddy's data (according to his Astrobin page) comes from the Deep Sky West remote imaging observatory in New Mexico at an altitude of 7400 feet (ca 2500 m). I doubt that Olly is that high up.

However, it now struck me that there could possibly be another scientific / technical reason for the difference in star colour. Paddy's images were taken with a camera with a Kodak KAF-8300 chip with 5.4 µm pixels while I believe that Olly used his Atik cameras with Kodak KAI-11002 chips with 9 µm pixels. This means that the well depth will be much larger in Olly's camera so it is possible that the small stars filled the wells for all three colours in Paddy's camera, resulting in a white star, while Olly's much larger wells did not fill up, so the filling of the wells varied according to the colour. If that is the case, then Olly's small yellow, red and blue stars are really yellow, red and blue. Just a thought and I am on deep water since I really do not know that much about CCD cameras.

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18 hours ago, Mr Bergman said:

Sorry for hijacking the thread, but I have a thought here. Hmm, so Ollys blue stars contain more blue? If we disregard scope types and Noels actions and think about this in a scientific way instead, there might be other reasons to star colour differences. Atmosphere eats up the blue light and a higher elevation of the object photographed increases its relative colour intensity. Did you compare your altitude above mean sea level and the elevation of the object when photographed? I might be very wrong here, but I suppose Olly is situated quite a bit higher up than most of us, and thus get a little star colour bonus. In reality, this might be so small that its unnoticeable, but at least its an interesting thought! 

 

 

18 hours ago, gorann said:

Interestingly, looking at your two images, it appears that only the small red/yelloe stars differ in colour. Nice to hear that you both feel relaxed about it, then I am relaxed too!

Good night since the sky is cloudy over here...

 

I think it is likely just different processing as mentioned previously.  I try to avoid the strong halos by preference.  All images will vary by location, gear, seeing etc.  If we are doing science then I would be concerned but just making a picture based on the data.  A little interesting but not this much :) 

16 hours ago, alan4908 said:

Amazing image Paddy.  I really do like the colours and your processing style, I must have a go at this object myself.

Alan

 

Thanks Alan - be worth a shot will keep eyes posted.

Paddy

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17 hours ago, MartinFransson said:

*Drooooool* :hiding:

Sorry. Not very constructive. But I really can´t do much more than drool when I see stuff this beautiful :)

 

Thanks Martin - the more i look the more i am pleased with it :)

15 hours ago, whipdry said:

Hello Paddy,

That's a really nice image.

 

Peter

 

Thanks Peter

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